All evolutionary biology stories

Female lower back has evolved to accommodate strain of pregnancy

404132862 — Wed, 12 Dec 2007 11:12:52 -0500

According to a new study by researchers at Harvard and the University of Texas at Austin, women's lower spines evolved to be more flexible and supportive than men's to increase comfort and mobility during pregnancy, and to accommodate the special biology of carrying a baby for nine months while standing on two feet.

‘Speed limit’ found on rate of evolution

jake — Mon, 22 Oct 2007 13:10:24 -0400

Harvard University scientists have identified a virtual “speed limit” on the rate of molecular evolution in organisms, and the magic number appears to be six mutations per genome per generation — a rate of change beyond which species run the strong risk of extinction as their genomes lose stability.

By modeling the stability of proteins required for an organism’s survival, Eugene Shakhnovich and his colleagues have discovered this essential thermodynamic limit on a species’ rate of evolution. Their discovery, published this week in the Proceedings of the National Academy of Sciences, draws a crucial connection between the physical properties of genetic material and the survival fitness of an entire organism.

Losos’ lizards give evolutionary clues in island experiments

50443248 — Mon, 01 Oct 2007 15:41:16 -0400

Tiny islets in the Bahamas have proven useful laboratories to illustrate natural selection’s effects on island lizards, which saw their legs lengthen, then shorten as ground-dwelling predators drove them into the trees.

The experiments capped years of research into a type of lizard called an anole on the Caribbean islands. The research, conducted by Jonathan Losos, the Monique and Philip Lehner Professor of the Study of Latin America, examined the relationships between lizards that shared similar habitats and characteristics but lived on different islands.

Losos described his research Tuesday (Sept. 18) during the kickoff talk in this year’s lecture series sponsored by the Harvard Museum of Natural History (HMNH).

First orchid fossil puts showy blooms at some 80 million years old

50443248 — Mon, 01 Oct 2007 16:27:21 -0400

Biologists at Harvard University have identified the ancient fossilized remains of a pollen-bearing bee as the first hint of orchids in the fossil record, a find they say suggests orchids are old enough to have coexisted with dinosaurs.

Their analysis, published this week (Aug. 29) in the journal Nature, indicates orchids arose some 76 to 84 million years ago, much longer ago than many scientists had estimated. The extinct bee they studied, preserved in amber with a mass of orchid pollen on its back, represents some of the only direct evidence of pollination in the fossil record.

A tale of two scholars: The Darwin debate at Harvard

50443248 — Tue, 02 Oct 2007 10:41:37 -0400

Few people have left a more indelible imprint on Harvard than Louis Agassiz.

An ambitious institution-builder and fundraiser as well as one of the most renowned scientists of his generation, he founded the Museum of Comparative Zoology (MCZ) and trained a generation of naturalists in the precise methods of observation and categorization developed in Europe. His wife Elizabeth Cary Agassiz, the other half of this Harvard power couple, was co-founder and first president of the Society for the Collegiate Instruction of Women, the precursor of Radcliffe.

Opossum genome shows 'junk' DNA source of genetic innovation

50443248 — Wed, 09 May 2007 16:51:38 -0400

A tiny opossum's genome has shed light on how evolution creates new creatures from old, showing that change primarily comes by finding new ways of turning existing genes on and off.

The research, by an international consortium led by the Broad Institute of MIT and Harvard, revises our understanding of genetic evolution. Scientists previously thought that evolution slowly changed the genes that create specific proteins. As the proteins changed, so did the creatures that owned them.

The current research shows that opossum and human protein-coding genes have changed little since their ancestors parted ways, 180 million years ago. It has been the regulation of their genes - when they turn on and off - that has changed dramatically.

"Evolution is tinkering much more with the controls than it is with the genes themselves," said Broad Institute director Eric Lander. "Almost all of the new innovation ... is in the regulatory controls. In fact, marsupial mammals and placental mammals have largely the same set of protein-coding genes. But by contrast, 20 percent of the regulatory instructions in the human genome were invented after we parted ways with the marsupial."

The research, released May 9 also illustrated a mechanism for those regulatory changes. It showed that an important source of genetic innovation comes from bits of DNA, called transposons, that make up roughly half of our genome and that were previously thought to be genetic "junk."

The research shows that this so-called junk DNA is anything but, and that it instead can help drive evolution by moving between chromosomes, turning genes on and off in new ways.

When fish first started biting

Tue, 10 Jul 2007 14:20:30 -0400

Before fish began to invade land, about 365 million years ago, they had some big problems to solve. They needed to come up with new ways to move, breathe, and eat.

Take the latter, for example. Fish usually pucker up and suck prey into their mouths. But air is 900 times less dense than water, so land-livers must bite into their food to get a meal. Researchers at Harvard University have just completed a study that gives a clear picture of how that change was made.

Humans hot, sweaty, natural-born runners

50443248 — Tue, 02 Oct 2007 15:39:11 -0400

Hairless, clawless, and largely weaponless, ancient humans used the unlikely combination of sweatiness and relentlessness to gain the upper hand over their faster, stronger, generally more dangerous animal prey, Harvard Anthropology Professor Daniel Lieberman said Thursday (April 12).

Just days before Monday’s 111th running of the Boston Marathon, Lieberman presented his theories of the importance of running to ancestral humans to explain why we’re the only species that voluntarily runs extraordinarily long distances, such as the 26.2 miles in the marathon.

Can science, religion coexist in peace?

50443248 — Tue, 02 Oct 2007 16:56:50 -0400

Almost 14 billion years after the big bang, and 3.5 billion years since the first bacteria appeared on Earth, humans occupy just one branch of the tree of life.

We share an evolutionary limb with other eukaryotes, creatures whose membrane-bound cells carry genetic material. Our biological neighbors developed over time just as we did, by the evolutionary forces of mutation and natural selection. They include plants, fungi, and slime molds.

Despite that humble company, said Martin A. Nowak, Harvard professor of mathematics and biology, humans have a profound "claim to fame" — language. He called the acquisition of complex expression "the only truly interesting thing to happen in the last 600 million years," and the most important of all evolutionary events.

Despite their heft, many dinosaurs had surprisingly tiny genomes

Wed, 11 Jul 2007 09:46:11 -0400

They might be giants, but many dinosaurs apparently had genomes no larger than those of a modern hummingbird.

So say scientists who've linked bone cell and genome size among living species and then used that new understanding to gauge the genome sizes of 31 species of extinct dinosaurs and birds, whose bone cells can be measured from fossilized bones.

The researchers, at Harvard University and the University of Reading, were led by Chris Organ and Scott V. Edwards at Harvard. They report their findings this week in the journal Nature.

Pressured by predators, lizards see rapid shift in natural selection

Thu, 12 Jul 2007 09:30:50 -0400

Countering the widespread view of evolution as a process played out over the course of eons, evolutionary biologists have shown that natural selection can turn on a dime - within months - as a population's needs change. In a study of island lizards exposed to a new predator, the scientists found that natural selection dramatically changed direction over a very short time, within a single generation, favoring first longer and then shorter hind legs.

Beetles' past tells volumes about tropical evolution

Fri, 13 Jul 2007 09:47:25 -0400

Experts seeking to explain the amazing diversity of the tropical rain forest have typically done so in two ways, viewing forests as either "evolutionary cradles" that encourage the rapid development of new species, or as "evolutionary museums" that allow species to accumulate over time.

New work by Harvard researchers on tropical beetles indicates that both views are right.

How Darwin's finches got their beaks

Thu, 12 Jul 2007 15:01:32 -0400

Darwin's finches are the emblems of evolution. The birds he saw on the Galapagos Islands during his famous voyage around the world in 1831-1836 changed his thinking about the origin of new species and, eventually, that of the world's biologists.

Darwin wondered about the changes in shape of bird beaks from island to island. So-called cactus finches boast longer, more pointed beaks than their relatives the ground finches. Beaks of warbler finches are thinner and more pointed than both. These adaptations make them more fit to survive on available food.

Monkey see, monkey infer

70652986 — Mon, 26 Mar 2007 06:26:58 -0400

Monkeys keep turning out to be smarter than people think they are. Researchers have shown that they can count to four and are aware of differences between languages like Dutch and Japanese, even though they don't known what is being said. Now, Harvard psychologists find that monkeys can draw correct conclusions about novel situations. For example, shown a white towel that turns blue, a blue knife, and a glass of blue paint, they can figure out that the paint, not the knife, is responsible for the change in color.

"Our studies reveal a striking continuity between humans and monkeys in their capacity to draw causal inferences without the help of familiarity with the events or situation," says Marc Hauser, a Harvard professor of psychology. "This ability highlights the richness of the monkey mind in terms of its understanding of the material world."

Hauser has been working with a colony of free-ranging rhesus monkeys on an island off Puerto Rico for many years. He and Bailey Spaulding, formerly a student of his, tested individual adult males and females of the colony on their ability to figure out cause and effect in unfamiliar situations.

In their experiments, they used a glass of water and a knife along with a whole apple and an apple cut in half. The knife can halve the apple, but the water can't. Do the monkeys grasp this?

In one set of tests the monkeys saw a glass of water and two whole apples. Then they viewed a knife being lowered and the apple cut in half. These are two perfectly plausible situations. Next, they saw the glass of water and two halves of an apple. Following this, a knife was lowered, and two apple halves seemingly became a whole apple.

To a human, even an infant who had never seen such things before, the last two apparent happenings would never really happen. Can monkeys infer the same outcomes? Evidently, the answer is "yes." They looked longer when a glass of water appeared to cut the apple than when a knife seemed to do the same. The longer look signaled disbelief.

Wakeley examines ancestral lines

70652986 — Mon, 26 Mar 2007 06:26:51 -0400

John Wakeley is devising new ways to trace the evolutionary road taken by humans and the creatures with whom we share planet Earth by creating new models that examine how DNA has changed over time.

A theoretical population geneticist, Wakeley's research focuses on how our DNA changes as it is passed from generation to generation. He is examining how the tendency of humans to live in groups separated by ethnicity or by physical barriers like mountains and rivers affects DNA's random changes.

Understanding groupings of individuals can be critical to figuring out why our DNA carries particular patterns today. That's because changes in patterns of genetic variation due to genetic drift - one of the major forces behind evolution - occur more rapidly in smaller populations and subpopulations.